![Xiaotian Feng](/assets/img/avatar_default.png)
There's a circular locking dependency: ---> isdn_net_get_locked_lp --->lock &nd->queue_lock --->lock &nd->queue->xmit_lock ..................... ---->unlock &nd->queue_lock ---> isdn_net_writebuf_skb (called with &nd->queue->xmit_lock locked) ---->isdn_net_inc_frame_cnt ---->isdn_net_device_busy ----> lock &nd->queue_lock This will trigger lockdep warnings: ======================================================= [ INFO: possible circular locking dependency detected ] 2.6.32-rc4-testing #7 ------------------------------------------------------- ipppd/28379 is trying to acquire lock: (&netdev->queue_lock){......}, at: [<e62ad0fd>] isdn_net_device_busy+0x2c/0x74 [isdn] but task is already holding lock: (&netdev->local->xmit_lock){+.....}, at: [<e62aefc2>] isdn_net_write_super+0x3f/0x6e [isdn] which lock already depends on the new lock. ....... We don't need to lock nd->queue->xmit_lock to protect single isdn_net_lp_busy(). This can fix above lockdep warnings. Reported-and-tested-by: Tilman Schmidt <tilman@imap.cc> Signed-off-by: Xiaotian Feng <xtfeng@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
153 lines
4.9 KiB
C
153 lines
4.9 KiB
C
/* $Id: isdn_net.h,v 1.1.2.2 2004/01/12 22:37:19 keil Exp $
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*
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* header for Linux ISDN subsystem, network related functions (linklevel).
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*
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* Copyright 1994-1999 by Fritz Elfert (fritz@isdn4linux.de)
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* Copyright 1995,96 by Thinking Objects Software GmbH Wuerzburg
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* Copyright 1995,96 by Michael Hipp (Michael.Hipp@student.uni-tuebingen.de)
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*
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* This software may be used and distributed according to the terms
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* of the GNU General Public License, incorporated herein by reference.
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*
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*/
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/* Definitions for hupflags: */
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#define ISDN_WAITCHARGE 1 /* did not get a charge info yet */
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#define ISDN_HAVECHARGE 2 /* We know a charge info */
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#define ISDN_CHARGEHUP 4 /* We want to use the charge mechanism */
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#define ISDN_INHUP 8 /* Even if incoming, close after huptimeout */
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#define ISDN_MANCHARGE 16 /* Charge Interval manually set */
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/*
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* Definitions for Cisco-HDLC header.
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*/
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#define CISCO_ADDR_UNICAST 0x0f
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#define CISCO_ADDR_BROADCAST 0x8f
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#define CISCO_CTRL 0x00
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#define CISCO_TYPE_CDP 0x2000
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#define CISCO_TYPE_SLARP 0x8035
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#define CISCO_SLARP_REQUEST 0
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#define CISCO_SLARP_REPLY 1
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#define CISCO_SLARP_KEEPALIVE 2
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extern char *isdn_net_new(char *, struct net_device *);
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extern char *isdn_net_newslave(char *);
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extern int isdn_net_rm(char *);
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extern int isdn_net_rmall(void);
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extern int isdn_net_stat_callback(int, isdn_ctrl *);
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extern int isdn_net_setcfg(isdn_net_ioctl_cfg *);
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extern int isdn_net_getcfg(isdn_net_ioctl_cfg *);
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extern int isdn_net_addphone(isdn_net_ioctl_phone *);
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extern int isdn_net_getphones(isdn_net_ioctl_phone *, char __user *);
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extern int isdn_net_getpeer(isdn_net_ioctl_phone *, isdn_net_ioctl_phone __user *);
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extern int isdn_net_delphone(isdn_net_ioctl_phone *);
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extern int isdn_net_find_icall(int, int, int, setup_parm *);
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extern void isdn_net_hangup(struct net_device *);
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extern void isdn_net_dial(void);
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extern void isdn_net_autohup(void);
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extern int isdn_net_force_hangup(char *);
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extern int isdn_net_force_dial(char *);
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extern isdn_net_dev *isdn_net_findif(char *);
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extern int isdn_net_rcv_skb(int, struct sk_buff *);
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extern int isdn_net_dial_req(isdn_net_local *);
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extern void isdn_net_writebuf_skb(isdn_net_local *lp, struct sk_buff *skb);
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extern void isdn_net_write_super(isdn_net_local *lp, struct sk_buff *skb);
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#define ISDN_NET_MAX_QUEUE_LENGTH 2
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#define ISDN_MASTER_PRIV(lp) ((isdn_net_local *) netdev_priv(lp->master))
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#define ISDN_SLAVE_PRIV(lp) ((isdn_net_local *) netdev_priv(lp->slave))
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#define MASTER_TO_SLAVE(master) \
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(((isdn_net_local *) netdev_priv(master))->slave)
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/*
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* is this particular channel busy?
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*/
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static __inline__ int isdn_net_lp_busy(isdn_net_local *lp)
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{
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if (atomic_read(&lp->frame_cnt) < ISDN_NET_MAX_QUEUE_LENGTH)
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return 0;
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else
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return 1;
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}
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/*
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* For the given net device, this will get a non-busy channel out of the
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* corresponding bundle. The returned channel is locked.
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*/
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static __inline__ isdn_net_local * isdn_net_get_locked_lp(isdn_net_dev *nd)
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{
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unsigned long flags;
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isdn_net_local *lp;
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spin_lock_irqsave(&nd->queue_lock, flags);
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lp = nd->queue; /* get lp on top of queue */
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while (isdn_net_lp_busy(nd->queue)) {
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nd->queue = nd->queue->next;
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if (nd->queue == lp) { /* not found -- should never happen */
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lp = NULL;
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goto errout;
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}
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}
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lp = nd->queue;
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nd->queue = nd->queue->next;
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spin_unlock_irqrestore(&nd->queue_lock, flags);
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spin_lock(&lp->xmit_lock);
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local_bh_disable();
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return lp;
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errout:
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spin_unlock_irqrestore(&nd->queue_lock, flags);
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return lp;
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}
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/*
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* add a channel to a bundle
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*/
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static __inline__ void isdn_net_add_to_bundle(isdn_net_dev *nd, isdn_net_local *nlp)
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{
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isdn_net_local *lp;
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unsigned long flags;
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spin_lock_irqsave(&nd->queue_lock, flags);
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lp = nd->queue;
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// printk(KERN_DEBUG "%s: lp:%s(%p) nlp:%s(%p) last(%p)\n",
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// __func__, lp->name, lp, nlp->name, nlp, lp->last);
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nlp->last = lp->last;
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lp->last->next = nlp;
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lp->last = nlp;
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nlp->next = lp;
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nd->queue = nlp;
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spin_unlock_irqrestore(&nd->queue_lock, flags);
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}
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/*
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* remove a channel from the bundle it belongs to
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*/
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static __inline__ void isdn_net_rm_from_bundle(isdn_net_local *lp)
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{
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isdn_net_local *master_lp = lp;
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unsigned long flags;
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if (lp->master)
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master_lp = ISDN_MASTER_PRIV(lp);
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// printk(KERN_DEBUG "%s: lp:%s(%p) mlp:%s(%p) last(%p) next(%p) mndq(%p)\n",
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// __func__, lp->name, lp, master_lp->name, master_lp, lp->last, lp->next, master_lp->netdev->queue);
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spin_lock_irqsave(&master_lp->netdev->queue_lock, flags);
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lp->last->next = lp->next;
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lp->next->last = lp->last;
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if (master_lp->netdev->queue == lp) {
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master_lp->netdev->queue = lp->next;
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if (lp->next == lp) { /* last in queue */
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master_lp->netdev->queue = master_lp->netdev->local;
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}
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}
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lp->next = lp->last = lp; /* (re)set own pointers */
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// printk(KERN_DEBUG "%s: mndq(%p)\n",
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// __func__, master_lp->netdev->queue);
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spin_unlock_irqrestore(&master_lp->netdev->queue_lock, flags);
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}
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